I dont think its possible using the current system - a pokemon MMO would be primarily PvP and in the case of pokemon, without at least a considerable overhaul to the battle system (turn based battles on a pay-to play MMO? theres already a freeware pokemon MMO mind you) and i just dont see it working out. At least i think the system would have to get a far more customizable aspect to better atune for the whole "MMO" aspect.
It can be done, especially if it expands considerably with respect to the pokemon universe ( Game moderators / paid employees being gym leaders, perhaps? assign yourself to a gym for perks? etc), but right now i'd say no. Perhaps in 1 or 2 more poke-generations from now, when we get more variety in the battle system - perhaps stance-attacks? i.e. defense curl powers up rollout, why not allow different variations of other attacks? tail whip working as a pseudo-fly as seen in the anime? Agility powering up speed-based moves? etc.
And regarding maplestory - while yes the game is targetted at the younger crowd, there is a rediculously large portion of the community that are college players and older. Hell, more than half the people who i've played with are at bare minimum 16 years old.
um..stuff
